. In this case, the Court is considering the question of whether detained immigrants are entitled to a timely bond hearing and possible release from custody, like nearly any U.S. citizen who is detained by law enforcement. Eric Thayer/Getty Images

The U.S. Supreme Court on Tuesday heard arguments in what could be one of the most significant immigrant rights cases in years. No, it wasn’t a challenge to the administration’s multiple Muslim travel bans, though indirect references to the bans were scattered throughout oral arguments. Instead, Tuesday’s case sought to answer the important question of what—if any—rights immigrants have to a bond hearing after detention.

Like Sessions v. Dimaya on Monday,Jennings v. Rodriguez is a carry-over case from last term, when the judges deadlocked 4 to 4 on how to resolve the issue of what, if any, due process rights detained immigrants have. And as in Dimaya, Justice Neil Gorsuch is likely to provide the deciding vote.

There are a variety of statutes that empower the federal government to detain immigrants entering the country. In this case, the Court is considering the question of whether detained immigrants are entitled to a timely bond hearing and possible release from custody, like nearly any U.S. citizen who is detained by law enforcement. Bonds are monetary promises that, if you are released from jail before the court hears your case, you will return once the court is ready. Because immigration courts are chronically backlogged, no bond hearing means that immigrants might wait in detention until the court can hear their case. And in some cases, that wait can take years. Of course, even those who are granted a prompt bond hearing may find it very difficult to produce enough money to be released.

Jennings is a class-action challenge to lengthy immigration detentions without any opportunity for release on bond. The attorneys representing Alejandro Rodriguez and other members of the class argue that the wait for a bond hearing for those in detention is unconstitutional. Rodriguez was held for more than three years before having a bond hearing; the government ultimately determined he could remain in the United States. Another member of the class, a torture victim from Ethiopia, sought asylum in the United States but was detained by the government on the grounds that his proof of identity was insufficient, before eventually being granted asylum by an immigration court.

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After Rodriguez and the others sued, a federal district court issued an order requiring prompt bond hearings for immigrant detainees. The U.S. Court of Appeals for the Ninth Circuit mostly agreed, and ruled that immigration judges must provide a bond hearing at least every six months, and that a noncitizen must be released from detention unless the government can provide clear and convincing evidence that the noncitizen is a flight risk or a danger to public safety. In 2016 the Court agreed to take the case, but could not reach a consensus after oral arguments. It then ordered the case be carried over to this term. Tuesday’s arguments illustrated just how contentious and unsettled the issue is, likely indicating why the justices were unable to find consensus last term.

Arguing on behalf of the government, Deputy Solicitor General Malcolm Stewart faced his toughest questions from Justice Sonia Sotomayor. From the beginning of arguments, she pressed Stewart to explain the differences between immigration detention and criminal detention, and why some immigrants can be subject to what the liberal justices on the court characterized as effectively indefinite detention. “[In] what other area of law have we permitted a government agent on his or her own, without a neutral party looking at that decision, to detain someone indefinitely?” she asked.

Stewart pushed back on Sotomayor’s characterization, suggesting some immigrant detainees are released expeditiously, but that clearly was not enough to satisfy Sotomayor’s questions.

“Perhaps let’s … answer this question: In which ways [are] immigration detention different than criminal detention?” asked Sotomayor. ” I mean, I—I understand right now that when you detain [immigrants], you put them in orange suits, they are shackled during visitation and court visits, they are subject to surveillance and strip searches, they are referred to be number, not by name,” Sotomayor continued. “So in which ways [are] immigration detention different than criminal detention?”

The Trump administration’s response was unsettling, to say the least: “Well, I think the—the real difference is the justification for the detention.”

Let’s be very clear here. Immigration proceedings are specifically not criminal proceedings, even if sometimes they walk and talk like them. And while the types and extent of constitutional protections for immigrants vary on a whole bunch of factors, including an immigrant’s specific status in this country, Tuesday’s argument reflected a clear intent by the Trump administration to elide, or erase altogether, the line between immigration law and criminal law. In other words, the differences extend far beyond justification alone.

The government also faced heated questioning from Justice Stephen Breyer. Breyer, who is quite vocal about the need for serious reforms in our criminal justice system, was positively gobsmacked that the government would argue it has the power to detain immigrants for as long as it sees fit.

“We detain people whenever we stop them for Miranda briefly,” said Breyer, referring to a stop for a probable cause such as speeding in a vehicle. “We detain them when we arrest them. Normally when you detain somebody … in most cases, you’d give them a bail hearing, all right?”

Breyer continued, getting more agitated as he pressed Stewart. “And so what’s the basis for reading the word ‘detained’ sometimes to allow bail hearings at the discretion of the [immigration] agency; other times not to allow bail hearings and keeping the people possibly for a year, a year and a half, in a jail cell without—sorry, I don’t mean my voice to rise—but—but without even a bail hearing?”

The Trump administration had no good answer for Breyer’s questions because there are none. Its basic position is that immigrant detainees are effectively entitled to no due process rights under the law.

The conservative justices for the most part were very staid during arguments. Chief Justice John Roberts suggested a possible analogy to speedy trial rights here. That’s a tempting argument to fall into, but one that assumes from the start that immigrants are criminals and that deportation proceedings are thus criminal rather than administrative. Justice Samuel Alito was searching for the bright-line test the government could use to determine when holding someone in jail without a bond hearing could be constitutional.

As usual, Justice Clarence Thomas said nothing.

A decision in the case isn’t likely until spring, and by that time we could already have the legal challenges to Trump’s latest travel ban racing up the federal appellate circuits. And while Jennings is not about the Muslim ban, it has all the ingredients of those future arguments: What exactly is the power of the executive to set immigration policy, and when can that policy run afoul of constitutional due process protections?

The fact that the government argued there are no due process rights in these cases is not just disturbing; it is a misstatement of the law and a tip of its hand on how it plans to proceed in defending future immigrant rights cases. The real question is whether there are enough justices on the Supreme Court who see the administration laying this groundwork and are willing to push back against it. After Tuesday’s arguments, that remains an open question.